This section briefly deals with some other scientific disciplines which the Iranians were engaged in, like engineering, physics, chemistry, etcetera.As per historical reports as well as archeological researches carried out on various available ancient inscriptions, the Iranians were one of the oldest existing peoples to have engaged in activities like architecture, digging subterranean water canals (qanāt) and making instruments used in wars. It is well-known that an Iranian engineer called Artākheh (Artachaies, in Latin) masterminded the excavation of a waterway in the isthmus of Mount Athos for the army of the Achaemenian king, Xerxes I (Khashāyārsha, in Persian) to pass. The Iranian sage, Estānce, who had accompanied Xerxes to Greece and who later became the head priest of the Egyptian temples was also apparently skilled in some scientific techniques and it is said that the Greeks learnt about witchcraft through his works. It has also been recorded that a chemist by the name Jāmasp wrote a book on chemistry and presented it to the Sassanid king, Ardeshir I (or Ardeshir Bābakān).During the Islamic period, too, the Iranians engaged in researching and writing books in these disciplines and particularly gained prominence in mechanics, chemistry and the extraction of heavy water. Nobakht, Fazāri, and Tabari (‘Amr bin Farkhān), and Mashāllah Yahudi Irani were in charge of geometrical calculations and the planning of the construction of Baghdad. Fārābi wrote an important treatise on chemistry entitled “Fi Wojub-e Sanā’ah al-Kimiyā” (On the Necessity of Alchemy), and in another article expressed his views on the mechanism of “seeing”. The book, “Al-Hiyal Banu Musā”, is the most outstanding piece of work in mechanics, belonging to the Islamic era. In this book, the author has discussed the structure and the functioning of some automatic instruments.Mohammad bin Zakariyā al-Rāzi was the first chemist to have applied his knowledge of chemistry in the filed of medicine. He had carried out significant researches on gravity through balance in different liquids, calling it “Al-Mizān al-Tabi’i”. He has been known to have written numerous treatises in chemistry. One of these treatises entitled, the “Safar al-Asrār”, contains a list of 25 chemical instruments. Rāzi had even made some efforts towards the classification of chemical-mineral elements.It has been recorded that Neyrizi wrote a book on celestial beings. Neyrizi’s commentaries on some atmospheric phenomena are indicative of his knowledge of radiation physics. Kāteb-e Khwarazmi’s book, the “Mafātih al-Olum”, contains interesting topics regarding alchemy. Similarly, Karaji’s book “Anbāt al-Miyah al-Khafiyah is a masterpiece in engineering, in general, and on irrigation techniques in particular wherein some exact calculations have been given for assessing the slope of subterranean canals, etcetera. In his book “Fi Radd-e al-Kimiyā” (On the Rejection of Alchemy), Ibn Sinā has rejected the idea of the transformation of certain elements into other elements and has considered it impossible. Ibn Sinā’s views on the mechanism of “seeing”, the impact of cold and heat on the temperature of solid and dry substances, the mechanism of the formation of rainbow, and some of the atmospheric phenomena are of considerable importance. Interestingly, Ibn Sina has been known to combine the views of Theophrastus and Aristotle on different natural sciences in order to arrive to some conclusions. Abu al-Hekam Kāthi, too, was a proficient chemist who wrote an important treatise on alchemy entitled “’EIn al-San’ah wa ‘Oun al-Sanā’ah” in c. 425 AH.In a treatise entitled “Afrād al-Maqāl”, Abu Reihan Biruni rejected some of Aristotle’s erroneous beliefs in the field of physics by resorting to a few scientific experiments. He succeeded in calculating the density of 18 precious stones and metals with astonishing precision and was of the opinion that the Sind Valley was, in all probability, originally a riverbed that had been gradually filled with sediment. He had also discovered that light traveled much faster than sound. By experimenting on the law of equilibrium in fluids he was able to explain the functioning of water springs and artesian wells. In his book, “Āthār al-Bāqiyah”, Al-Biruni had rejected the theory that insects were produced from different types of feces and had presented a discussion on some types of freaks, referring to what is today popular as Siamese or conjoined twins while also referring to the existing order in the number of petals. Keeping in view the extent of the matters discussed by Abu Mansur Mowaffaq Heravi in his book on pharmacology entitled, the “Al-Abniyah ‘An Haqāyeq al-Adwiyah” (written in 447 AH), he can be considered as one of the greatest of Muslim chemists. In this book he has provided extensive information on the properties of different minerals, the difference between sodium carbonate and calcium carbonate, orpiment, copper oxide, silicic acid, crude antimony, the poisonous properties of copper and lead compounds, the depilatory properties of lime, and the composition of plaster of Paris and its application in surgery. Mozaffar Esfazāri invented a unique cyclometer of high precision. His views on atmospheric phenomena are also very interesting and he was the first person to have spoken about the symmetrical structure of snowflakes. Abd al-Rahmān Khāzani was an outstanding Iranian physicist of the Islamic period who also wrote important books in astronomy and chronology. His book, the “Mizān al-Hekmah”, is considered to be one of the most important works in physics of the Middle Ages. As per available information, it was much before Roger Bacon that this Muslim scholar had discovered that the weight of a particular quantity of fluid would increase with the reduction in its height. He had also carried out interesting researches on the density of substances. Sharaf al-Din Mas’udi’s books, the “Āthār-e ‘Olvi” and the “Jahān-e Dānesh”, both of which were written in Persian, as well as ‘Amrbin Sahl Sāwi’s treatise “Al-Resālah al-Sanjariyah” were among the very important works written on natural sciences. Fakhr Rāzi, too, was well-versed in physics and had written on the application of mechanics and hydrostatics in his book, the “Jāme’ al-Olum” (Jāme’ Setini). Rezwān bin Mohammad, popularly known as Ibn Sā’āti, had written a book on the functioning and maintenance of the clock made by his father, which was mounted atop one of the gates of Damascus. Along with the book “Jazari” this work is considered as the most important source on clocks made during the Islamic period.Nasir al-Din Tusi had written extensively on rainbows, the reflection and refraction of light, the impact of cold and heat on the color of dry and solid substances, etcetera. His student, Qotb al-Din, too, in two separate books entitled “Al-Tohfah Al-Shāhiyah” and “Nahāyah al-Edrāk” has included some very important ideas on radiation physics, aerial mechanics, and the measurement of the diameter of the earth. Similarly, in his two books “’Ajāyeb al-Makhluqāt” and Āthār al-Belād”, Zakariyā Qazvini has made considerable contribution to physiology (particularly in explaining the process of seeing), chemistry, botany, celestial phenomena, and other natural sciences. Noble theories have been presented by Kamāl al-Din Fārsi in his book “Tanqih al-Manāzer” that had for a long time attracted the attention of many scholars. As regards petrology and mineralogy, Al-Biruni’s book, the “Al-Jamāher fi Ma’refah al-Jawāher” is undoubtedly the most outstanding piece of work produced by an Iranian scholar. In his outstanding work, the “Kitab al-Shifa” (Book of Healing), Ibn Sinā, too, has dedicated a chapter to mineralogy entitled, “Al-Ma’āden wa al-Āthār al-‘Olwiyah”. Last but not the least, Nasir al-Din Tusi, too, had written a book on this subject entitled “Tansukhnāmeh Ilkhāni”, the most important sources of which were Abu al-Qāsem Abdollah Kāshāni’s books, “’Arāyes al-Jawāher” and “Nafāyes al-Atāyeb”.